The present disclosure relates generally to voice and data communications, and more particularly, to a wireless system and method for providing communication services to a wireless mobile user of a wireless access network based on one technology through a wireless core network based on a different technology.
A wireless network may be composed of two sub-networks. The first sub-network may be a Radio Access Network (RAN) which handles radio related issues, such as assigning radio resources to establish and maintain a communication session with a mobile communications device upon a request for service. The second sub-network may be a Core Network (CN) which links a user of a mobile device to a wireline network. The wireless network, its sub-networks, and mobile devices within the network may communicate using a standardized set of signals and commands known as a specification.
Available specifications for the wireless network may specify that the RAN and the CN of the wireless network are based on the same wireless technology. For instance, if the RAN and the CN are based on a technology such as Global System for Mobile communications (GSM), a mobile subscriber using a GSM compliant device may utilize the network. Likewise, if the RAN and the CN are based on a technology such as code division multiple access 2000 (CDMA2000), a mobile subscriber using a CDMA2000 compliant device may utilize the network.
However, due in part to incompatibilities between different specifications, such as GSM and CDMA2000, a mobile device may only be able to utilize networks based on a particular specification. For example, a mobile device compliant with GSM cannot access a network based on CDMA2000. Accordingly, the mobile device may be unable to provide a user with service if a GSM network is not available. This may limit the mobile device to a geographical service area that includes networks that support the particular wireless technology of the mobile device. As the number of differing existing and proposed specifications grows, this limitation may become increasingly problematic.
One approach that has been developed to overcome the limitations imposed by multiple specifications utilizes a dual-mode wireless mobile device that can operate in networks based on different wireless technologies. For example, the mobile device may operate using either CDMA or GSM, and so may switch its mode of operation between CDMA and GSM depending on the technology underlying the network in which the mobile device is currently located. Accordingly, the mobile device may utilize GSM when in a GSM-based network and switch to CDMA when in a CDMA-based network.
However, this dual-mode solution introduces additional complications. For example, a CDMA-based RAN may offer a relatively high quality of service compared to a GSM-based RAN. Therefore, the quality of service offered by the mobile device may be downgraded when moving from the CDMA network into the GSM network. While this degradation in service quality enables the service to be maintained, it presents an undesirable compromise. In addition, such degradation may result in lower data rates on a radio link (e.g., a link between the mobile device and a radio tower in a network), lower revenue for the network operator, and a lower number of supportable subscribers. Network congestion can further increase the degradation. Accordingly, at some point, a mobile user switching to the GSM network while on a voice or data call may lose service. Another complication presented by the dual-mode solution is that CDMA2000 may offer a higher spectrum efficiency than GSM. From a network resource perspective, the GSM RAN may not utilize the available radio resources as efficiently as the CDMA RAN. Accordingly, such inefficiency may result in such undesirable factors as fewer simultaneous users and lower revenue. Therefore, what is needed is a method and system that can provide wireless service to a mobile device regardless of the underlying network technology. It is desirable that minimal service degradation occurs when the mobile device is moving from one network to another. It is also desirable to utilize RAN technologies that maximize service quality and revenue. Furthermore, it is desirable to minimize changes to existing network architectures and to be cost effective.